Flexible goggles having a flexible housing in which a lens structure is mounted are well known. Individuals often wear such goggles to protect their eyes or to improve their vision when participating in a sport or a recreational activity, such as skiing or motorcycle racing. Such goggles are commonly used by skiers or motorcyclists to protect their eyes from wind and precipitation.
Goggles are shaped to fit flush against the contours of the human face. When worn by a user, a generally closed chamber is defined between the goggle's lens structure and the wearer's face. As time passes, moisture evaporating from the wearer's face increases the relative humidity of the air in the chamber. As the relative humidity increases, so does the dew point, or the point at which water molecules will condense from a vapor phase to a liquid phase. When cold air surrounding the goggle reduces the temperature of the lens structure of the goggle to a temperature below the dew point, water condenses on the inner surface of the lens structure. The condensate on the inner surface of the lens structure decreases the wearer's vision and makes it more difficult, or impossible, for the wearer to participate in the sport or recreational activity.
One technique for reducing condensation in the chamber is by using a double-paned lens structure to insulate the internal surface of the lens structure from the cold, external temperature. One conventional double-paned lens structure is referred to as a “thermal lens” and is formed of an inner lens and an outer lens. The inner and outer lenses are assembled and spaced in parallel relation by a spacer. The spacer is typically made of closed cell, flexible foam which is bonded to the inner and outer lenses in a fashion so as to seal against both.
One conventional method of forming the spacer is by die cutting a sheet of flexible foam material having a pressure sensitive adhesive bonded to each side thereof to define the shape of the spacer. After die cutting, the formed spacer is manually applied to one of the lenses followed by bonding the other lens to form a double-paned lens structure. However, the die cutting process wastes material because only a portion of the sheet is required to form the spacer. Also, manually applying the die cut spacer is tedious, time consuming, and prone to positioning errors that reduce the quality of the resulting product. Furthermore, spacers formed of flexible foam type materials are subject to delaminating from the lenses, resulting in fogging of the lens structures.
Another conventional method for forming the spacer is by injection molding a plastic spacer onto a first lens. During this process, the plastic is injected into a die that defines the shape of the spacer and upon curing the plastic bonds to the first lens. The injection molding process requires a die that is specifically designed for the particular lens geometry that the spacer is formed on. A second lens is then assembled with the first lens that includes the spacer thereon. The spacer is bonded to the second lens by radio frequency (RF) welding or gluing. Such a method is employed to form the spacer of the double-paned lens structure used in various goggles commercially available from Carrera Sport. However, double-paned lenses formed by this method are very rigid due to the inherent rigidity of the plastic formulation compatible with the injection molding process that is used to form the spacer. The rigidity of the spacer results in a rigid double-paned lens structure that will not adequately form fit to all potential wearer's faces or can cause substantial discomfort to the wearer's face. Furthermore, the die required for injection molding is expensive to fabricate and is specific to a particular lens geometry. Thus, injection molding is not a particularly versatile process for forming the spacer.
Accordingly, there is a need for a method of forming a lens structure by a relatively inexpensive process that produces a lens structure that helps alleviate the problem of condensation in the chamber of the goggle. It would also be desirable that the method for forming the spacer of the lens structure is adaptable to a variety of lens geometries. Furthermore, it would be desirable that the lens structure have the ability to comfortably form fit to the wearer's face.